Resistance Risk

Limited UV resistance risks of environmental stress cracking heat and creep sensitivity low rigidity high shrinkage, difficult gluing. 

The groups are focused on major areas of fungicide chemistry that have presented themselves as real or potential resistance risks in agriculturally important crops. These are ... 

Gentian violet Methyl/crystal violet Good antibacterial activity, low resistance risk, antiinflammatory potential High toxicity in concentrations >1%, intense color... 

Fig. 4 Components of a qualitative antimicrobial resistance risk assessment. (From Ref. f)...

Risk Evaluation. The main factors influencing the resistance risk are shown in Table I. Characteristics and relative importance of the various different elements have been described by several authors (9, 10, 11. 12). Whereas management risk factors can be influenced, this is not true for the product- and pathogen-inherent factors. However, thorough and reliable evaluation of both product-and pathogen-related factors is needed to establish the true basis for the design of any realistic strategy. Needless to say, this is a difficult task. 

Table I. Factors Influencing Resistance Risks After Staub and Sozzi (12)...

Determination of Inherent Resistance Risk Risk Evaluation and Design of Resistance Strategy Coordi- nation Between Manufac- turers Implemen- tation Communi- cation, Education Moni- toring Adaption, New Design of Strategy... 

In view of low success rate, need to develop new products despite inherent resistance risks... 

Keiding, J., Jespersen, J.B. and El-Khodary, A.S. (1991) Resistance risk assessment of two insect development inhibitors, diflubenzuron and cryomazine, for control of the house fly Musca domestica. Part 1 larvicide tests with insecticide-resistant laboratory and Danish field populations. Pesticide Science, 32, 187-206. 

Resistance Risk Assessments Before Market Introduction... 

As the molecular target site of Qol fungicides was known quite early, this fimgicide group is one of the rare examples which allowed extensive resistance risk assessments well before and during the market laimch of the first representatives. 

Although early studies on the resistance risk of Qols had detected a multitude of mutations aU lowering the sensitivity to Qol fungicides, up to now, besides the G143A mutation, only one further mutation could be proved in field isolates. At... 

Early (pre-launch) risk assessments were essentially not able to predict correctly the high resistance risk of Qol fungicides. This rehects a general problem with mutagenesis studies delivering mostly only limited informahon on the impact of a mutation on htness and competitiveness. 

Nagi DK, Yudkin JS. Effects of metformin on insulin resistance, risk factors for cardiovascular disease, and plasminogen activator inhibitor in NIDDM subjects. A study of two ethnic groups. Diabetes Care 1993 16 621-629. 

The contribution FRAC Mode of Action Classification and Resistance Risk of Fungicides (Chapter 12), starting with a short introduction on the history of fungicides, explains the importance of individual modes of action relative to their market penetration, their mechanisms and occurrence of resistance, the importance and occurrence of practical resistance on the management of fungicide resistance by FRAC (Fungicide Resistance Action Committee) and its recommendations to farmers related to the modes of action of the different fungicides. 

FRAC Mode of Action Classification and Resistance Risk of Fungicides... 

If molecules from different manufacturers have the same mode of action and if this mode of action bears at the same time a significant resistance risk, a FRAC... 

Based on the environmental and toxicological properties of a compound, a rather fixed frame is given that defines the maximum number of apphcations per season and area. The assessment of resistance risk must be done within this frame and the number of applications may be further reduced to adequately manage resistance risk. 

Appropriate resistance management tools have to be chosen and validated for each individual pathogen/fungicide combination and out of all available resistance risk modifiers. The EPPO Standard on Resistance Risk Analysis [17] lists the following tools for lowering the overall resistance risk ... 

B1 1 -Tubuline assembly in mitosis Methyl- benzimidazole carbamates Benomyl, carbendazim, thiophanat- methyl Broad spectrum fungicides high resistance risk... 

C3 11 Complex III cytochrome bcl (ubiquinol oxidase) at Qo site Qol fungicides Strobilurins and related Azoxystrobin, Pyradostrobin Mostly broad spectmm high resistance risk... 

I 12 FRAC Mode of Action Classification and Resistance Risk of Fungicides Table 12.11 Group F Fungicides interfering with lipid and membrane synthesis, cell wall deposition. 

Basidiomycetes, a pronounced curative activity and a moderate resistance risk are characteristics for DM Is and amines. Contrary to other inhibitors of fungal sterol biosynthesis, the G3 representative fenhexamid shows a rather narrow spectrum of activity, confined to Botrytis cinerea and the related pathogens Monilinia spp. and Sclerotinia spp. 

Table 12.17 Group U 2. Recently introduced fungicides with unknown mode of action and resistance risk.

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